loadbot/zec: Avoid using the same outputs.

zec will complain about double spends if sendtoaddress is used too soon
after mining a block. Use a mutex to make sure we always wait a second
after mining to send.

dex/testing/dcrdex/harness.sh

@@ -149,7 +149,7 @@ if [ $ZEC_ON -eq 0 ]; then
         {
             "base": "ZEC_simnet",
             "quote": "BTC_simnet",
-            "lotSize": 100000000,
+            "lotSize": 1000000,
             "rateStep": 1000,
             "epochDuration": ${EPOCH_DURATION},
             "marketBuyBuffer": 1.2

dex/testing/loadbot/loadbot.go

@@ -99,8 +99,12 @@ var (
 	defaultMidGap, marketBuyBuffer float64
 	keepMidGap                     bool
 
-	processesMtx = sync.Mutex{}
-	processes    = []*process{}
+	processesMtx sync.Mutex
+	processes    []*process
+
+	// zecSendMtx prevents sending funds too soon after mining a block and
+	// the harness choosing spent outputs for zcash.
+	zecSendMtx sync.Mutex
 )
 
 func init() {
@@ -181,9 +185,18 @@ func returnAddress(symbol, node string) string {
 // mine will mine a single block on the node and asset indicated.
 func mine(symbol, node string) <-chan *harnessResult {
 	n := 1
-	// geth may not include some tx at first because ???. Mine more.
-	if symbol == eth {
+	switch symbol {
+	case eth:
+		// geth may not include some tx at first because ???. Mine more.
 		n = 4
+	case zec:
+		// zcash has a problem selecting unused utxo for a second when
+		// also mining. https://github.com/zcash/zcash/issues/6045
+		zecSendMtx.Lock()
+		defer func() {
+			time.Sleep(time.Second)
+			zecSendMtx.Unlock()
+		}()
 	}
 	return harnessCtl(ctx, symbol, fmt.Sprintf("./mine-%s", node), fmt.Sprintf("%d", n))
 }
@@ -449,7 +462,7 @@ func run() error {
 		if res.err != nil {
 			return "", fmt.Errorf("error getting %s address: %v", symbol, res.err)
 		}
-		return res.output, nil
+		return strings.Trim(res.output, `"`), nil
 	}
 
 	if alphaAddrBase, err = getAddress(baseSymbol, alpha); err != nil {

dex/testing/loadbot/mantle.go

@@ -391,7 +391,7 @@ func (m *Mantle) createWallet(symbol, node string, minFunds, maxFunds uint64, nu
 			}
 		}
 	}
-	<-harnessCtl(ctx, symbol, fmt.Sprintf("./mine-%s", node), "1")
+	<-mine(symbol, node)
 
 	// Wallet syncing time. If not synced within five seconds trading will fail.
 	time.Sleep(time.Second * 5)
@@ -400,8 +400,20 @@ func (m *Mantle) createWallet(symbol, node string, minFunds, maxFunds uint64, nu
 func send(symbol, node, addr string, val uint64) error {
 	var res *harnessResult
 	switch symbol {
-	case btc, dcr, ltc, doge, bch, zec:
+	case btc, dcr, ltc, doge, bch:
 		res = <-harnessCtl(ctx, symbol, fmt.Sprintf("./%s", node), "sendtoaddress", addr, valString(val, symbol))
+	case zec:
+		// sendtoaddress will choose spent outputs if a block was
+		// recently mined. Use the zecSendMtx to ensure we have waited
+		// a sec after mining.
+		//
+		// TODO: This is not great and does not allow for multiple
+		// loadbots to run on zec at once. Find a better way to avoid
+		// double spends. Alternatively, wait for zec to fix this and
+		// remove the lock https://github.com/zcash/zcash/issues/6045
+		zecSendMtx.Lock()
+		res = <-harnessCtl(ctx, symbol, fmt.Sprintf("./%s", node), "sendtoaddress", addr, valString(val, symbol))
+		zecSendMtx.Unlock()
 	case eth:
 		// eth values are always handled as gwei, so multiply by 1e9
 		// here to convert to wei.

dex/testing/zec/harness.sh

@@ -225,7 +225,7 @@ chmod +x "./start-wallet"
 
 cat > "./connect-alpha" <<EOF
 #!/usr/bin/env bash
-${CLI} -rpcport=\$1 -regtest=1 -rpcuser=user -rpcpassword=pass addnode 127.0.0.1:${ALPHA_LISTEN_PORT} add
+${CLI} -rpcport=\$1 -regtest=1 -rpcuser=user -rpcpassword=pass addnode 127.0.0.1:${ALPHA_LISTEN_PORT} onetry
 EOF
 chmod +x "./connect-alpha"